


Forbidden, but Oh So Good

by err0r_666



Category: Voltron: Legendary Defender
Genre: Alternate Universe - Modern Setting, During quarantine, Incest, Keith seduces Shiro, M/M, Oral Sex, PIV Sex, Sibling Incest, Trans Keith (Voltron), Virgin Keith (Voltron), afab language, i cant help myself im sorry, lol
Language: English
Status: Completed
Published: 2020-06-29
Updated: 2020-06-29
Packaged: 2021-03-04 00:42:03
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 2,134
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24674791
Author URL: https://archiveofourown.org/users/err0r_666/pseuds/err0r_666
Summary: The covid-19 pandemic send Keith and Shiro home from college for, god knows how long.
Relationships: Keith/Shiro (Voltron)
Kudos: 72





	Forbidden, but Oh So Good

**Author's Note:**

> I tweeted that I might write some sheithcest and one person replied so I’m writing this for you. 
> 
> Also, based on recent events because why not. *AFAB Language used*
> 
> Enjoy <3
> 
>   
> [Twitter](https://www.twitter.com/LoveSickLithium)

Life’s been stressful for all, Shiro’s sixth year into getting his PhD was cut short and moved online due to the pandemic that seemed to come out of nowhere. Keith’s freshman year, moved online as well.Their mother opts to stay at the clinic that she works at to protect both boys. Their father stays at the fire station for the same reasons, leaving them alone together. Keith and Shiro are adults, they can take care of themselves. 

They both have similar schedules, attend an online morning class, eat breakfast together, then more classes. Keith usually eats lunch in his room while doing homework and studying. Shiro doesn’t mind though, they eat dinner together so that makes up for it. 

Shiro doesn’t intend to lose all his muscle during the long stay at home, so he works out in their backyard after jogging around the neighborhood. He works out all his tensions and stress, but it doesn't seem for be working for his pent-up sexual frustration. Shiro's not the quietest when doing anything sexual, hell, everyone in the dorms knows that by now. 

It's been a whole month, and Shiro hasn't gotten off at all. Keith seems to notice, and for some reason it seems like Keith's clothes get smaller and smaller everyday. One day Keith's wearing sweatpants and the next he's wearing _really_ short shorts. Shiro notices immediately, well, Shiro's cock notices. 

Days continue like that, Shiro will wake up before Keith, start breakfast and Keith will come down to the kitchen in barely any clothes. It seems like everyday Shiros yelling at his throbbing, hard dick to calm down, always telling himself he can't lust over his _brother_. 

During lunch, Shiro's class is cut short, it doesn't take him long to be face down in a pillow, fucking his tight fist, wishing it was Keith. He's been way too pent up, too clouded by lust that Keith has unfortunately granted Shiro. He tries to be as quiet as possible but can't help but let out a couple moans every once in a while. 

A hot blush rises on Keith's cheeks as he hears the muffled moans next door. He decides to investigate, he's been trying to seduce his older brother for weeks now, might as well take advantage of this situation. Keith tip-toes over to the closed door that leads to Shiro's room, he presses he ear up to the door, trying to listen for any names, specifically his.

He barely hears it.

"Mm, fuck, Keith." 

It surprises him, but not too much. A hand dips down into his red underwear to stroke his clit and rub fingers between drenched folds. He's already soaked from hearing his brother moan out his name while getting off. This is so bad, so wrong, Keith shouldn't be doing this. But, it makes him more and more aroused. 

Shiro finishes before Keith with a loud moan, painting his sheets white with potent cum. Keith slides his ruined underwear off and decides to leave it as a present for Mr. Horny outside of his door before running off back to his room. Shiro finds them, assuming he dropped them while carrying his clothes from the dryer. He's about to bring them to Keith's room before his fingers touch something slick and sticky. Shiro decides against returning them and paints them white like his sheets. 

The next day, Keith arrives to the kitchen in tiny red shorts, a tight black crop top that does absolutely nothing to hide his nipple piercings, and black thigh-high socks. He acts like he didn't just leave his cum soaked panties in the hallway the day prior. 

"What's up with those socks?" Shiro tries to tease, very obviously aroused by Keith. "Might as well just wear pants," 

Keith responds by sticking his pierced tongue out at him. Fuck, Shiro's never noticed that before.

"How much longer till breakfast is ready? I'm hungry," Keith questions while he hops up to sit on the counter. "Just a minute, princess," Shiro teases again, knowing that Keith hates the pet name but loves it at the same time. 

Keith pouts, making Shiro's dick twitch, gods he's so cute, 

"By the way, have you seen any underwear? I lost my favorite pair while doing laundry yesterday," Keith questions. 

Shiro goes bright red. "Uh, no, I don't think so," he replies with as much composure as he can muster. 

"Huh, weird," Keith leans back against the cabinet, spreading his legs to show the wet spot thats appearing in the tight shorts that show the outline of his cunt so perfectly, obviously not wearing panties. 

Shiro can't handle it anymore, he finishes the last pancake before walking over to his younger brother and wrapping one hand around his tiny neck, his other hand reaching down to stroke Keith through his shorts. 

"What the fuck has been going on, princess?" Shiro asks, putting a little more pressure on Keith's clit. A high pitched moan escapes Keith's sweet lips. 

"N-nothing, I just missed my big brother," he explains knowing without a doubt what Shiro is talking about. "I just wanted to look good for him."

"By dressing like a slut everyday and leaving your dirty panties outside my door?" Keith blushes hard at that. Sometimes he a really big all talk no action guy, especially with his brother. Two fingers push past Keith's shorts and into his soaked cunt. 

Shiro picks Keith up effortlessly, carrying him upstairs, fingers still burred deep inside him. Keith moans desperately as he feels the fingers inside him curl up to abuse his g-spot.

He’s thrown on Shiro’s bed as they enter his room, legs falling open to present his cunt. Shiro catches a good glimpse of his brother for the first time in years and realizes how beautiful he is. 

Black, silky hair just reached past his shoulders, framing his perfect structured face perfectly. Though Keith hates it, the scar on his right cheek, caused by a childhood accident with Shiro, makes him just as stunning and unique. Captivating violet eyes looking desperate yet innocent as they stare back at the grey eyes admiring him. 

"Please..." Keith quietly exhales, his hand reaching down to stroke himself through the thin fabric of his shorts.

Shiro flips him over to be on his hands and knees, quickly tearing off his shorts to reveal the puffy, pink cunt that belongs to his brother. The thought flashes Shiro's mind for the hundredth time, _"_ _No Takashi, he's your brother"_ but his throbbing erection promptly rids of that thought. Shiro leans down to kitten lick at the already glistening folds, Keith moans in desperation, he's been too empty for too long. 

"Takashi _please,_ " Keith almost yells at him in agony of the teasing. Shiro's tongue just keeps on lapping up Keith's slick, occasionally stopping to flick over his clit, resulting in Keith moaning even more. 

"Think you've had enough princess?" Shiro asks as he pauses, lips and chin damp with Keith's arousal. Keith whines in response, face buried in the blankets that are laced with Shiro's scent. 

Keith's slender hands reach around to spread himself, presenting his cunt even more. "Please, Takashi, I need it so badly, I've been wanting you for so long. I'm so empty, _please!"_

Shiro chuckles, he's not planning on giving Keith his cock so easily. He grabs Keith's wrists, bending his elbows and placing his forearms parallel on the small of his back. "Be good for me and stay like that," Shiro walks over to his closet, picking out a black tie and binding Keith's arms together. 

He takes a step back to admire his stunning baby brother, ass in the air, cunt dripping with slick, even his asshole is inviting, everything about Keith is so perfect for Shiro. 

Keith whines more, wiggling his hips to try and entice Shiro to finally sink himself in, but that doesn't happen. Shiro likes to observe, he grabs Keith's plump ass and gives it a good smack, watching Keith wiggle even more.

Shiro grabs Keith's hair, bringing him to sit on his knees, looking deeply into Shiro's eyes with even more need than before. Keith's almost in tears by how desperate he is for the older man to fill his tight heat. Shiro leans in, taking his brothers lips into a deep kiss, Keith is so much smaller than Shiro that his tongue almost fills his whole mouth. 

He moans into the kiss as he feels Shiro's finger play with his creamy pussy, dipping his finger tips just slightly into him, just enough to tease. He whines more, wanting to feel Shiro's finger breach his hole.

Shiro breaks the kiss, setting Keith back down as he becomes a whiny, needy mess. Two fingers _finally_ enter Keith's sopping wet hole and begin to quickly abuse his g-spot. Keith moans _loud,_ it almost startles Shiro.

"How long has it been since you've had someone's cock fill you up, baby boy?" Shiro asks, fingers pumping in and out of Keith's tight cunt. 

He mumbles something but Shiro can't quite hear. "I can't hear you if you're face down, baby,"

"N-never," Keith whimpers out, ashamed.

Shiro's surprised to say the least, "Have you been saving yourself for me?" he asks, slowing his fingers down. 

Keith just whimpers again. "I've liked you more than a brother since we were little," he explains, a harsh blush painted his cheeks as he spoke. Shiro groans, Keith is just so absolutely perfect. He removes his fingers, licking them off which makes his younger brother blush even more. 

Shiro presses his bulge into Keith's backside, which makes him moan, before pulling his sweatpants and boxers down and rubbing the tip of his cock between Keith's folds. 

"Do you want it, baby?" Shiro asks, he answers by pushing himself back. They groan in unison as the first few inches of Shiro's thick cock breaches Keith's tight, virgin cunt. Shiro takes that as a yes and keeps pushing in. 

It's such a tight stretch, even with how slick Keith got it was still a bit painful for him. Shiro's cock seemed to go on forever, Keith's getting lightheaded with so much pleasure.

After what it feels like forever, he feels Shiro's balls press up against him and he's brought back to reality as he hears a deep groan come from behind him. Shiro pulls back slowly before thrusting back in, Keith's already a moaning, whimpering mess. 

Shiro's gripping Keith's hips so hard that they might bruise, thrusting faster and faster each time he pulls out. It doesn't take long for Keith's orgasm to start building, he's being pounded by his big brother at mind-blowing speed.

"Ta-Takashi, f-fuck, oh my god," he groans into the blankets. Shiro lets go of his hips and wraps his arms around Keith's shoulders and pulling him up to be pressed up against his chest. He's gone limp from how hard and fast Shiro's going. "Open your eyes, baby, I want you to look into my eyes as you cum," Shiro whispers in his ear. 

Keith didn't even know he closed his eyes, but it take almost all of his strength to open them. He moans even louder as he make eye contact with his brother. His cunt clenching tighter and tighter as he gets closer and closer to orgasm.

One hand reaches down to start stroking Keith's swollen clit, he screams in return, on the crest of his orgasm. Shiro doesn't stop looking into his brother eyes as he feels Keith tense and his cunt clench down harder than ever and a white wave of blinding pleasure washes over him. 

Shiro buries himself deep inside Keith and lets go. Hot, potent cum floods Keith's womb as Shiro fills him.

Keith's eyes close as he goes limp in Shiro's arms. He carefully unties his arms making sure to massage them a little before setting him back down. 

"You okay, baby?" Shiro asks when all he hears is panting coming from Keith. He whimpers as a reply, too fucked out to say anything. Shiro pulls out slowly, careful not to overstimulate the smaller male beneath him. He watches the cum pour out from Keith's newly unvirgin cunt, as he's about to leave to get a rag he hears a whimper come from Keith.

"P-please don't leave me.." Shiro barely hears Keith, he's scared, but he doesn't blame him, it's his first time. Shiro decides to clean up later and gets in bed with Keith. 

"Is this a one time thing?" Keith asks, fear still laced in his voice. "Only if you want it to be," Shiro replies. 

"No.. I don't want that, Takashi, I want you forever." he says as he cuddles up to Shiro's chest, strong arms wrapped protectively around him. 

"Then, you have me forever, baby." 

**Author's Note:**

> Ahh!! the fluff at the end (* >ω<)
> 
> I hope you liked!! Feel free to leave a kudos/comment!
> 
> Have a good day/evening/night! <3
> 
> [Twitter](https://www.twitter.com/LoveSickLithium)


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